Its up to you. For me PC upgrade means moving to offline controller / after my latest troubles with Pokeys/ . Otherwise any old cheap pc does excellent job. A day ago i bought a cheap offline controller from China to give it a try. Next on my list is trying the more expensive ones.

From the beginning to me a mach3 was not a reliable solution. Change this, forget that sequence of starting PC, then this, then that and all messes up. Not to speak of that the Mach3 screens f%%k up almost 100% on electricity stop suddenly. And if you have forgotten to make at least 3 backups, then you are in trouble. I will happily pay 500-800euro for any reliable solution without Mach3 or PC. Even if chinese. For now i will try the cheap ones ~180 euro, but at the moment i am searching for manuals and who really makes the ~500euro ones